Protection device for cannulae

ABSTRACT

A syringe has a body on which is mounted an end fitting fixed to a needle having a tip. A protective device for the syringe has a small-diameter sleeve fitting around the needle and having an inner end at the end fitting and an opposite outer end. This sleeve can move from a starting position with the outer end adjacent the body and exposing the needle tip and an end position with the outer end engaged over the needle tip. The sleeve is formed with at least one flexible extension having a free outer end generally level with the needle tip in the starting position. The sleeve is secured to the end fitting in the starting position by structure sufficiently weak that a traction applied to the flexible extension displaces the sleeve into the end position.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US national phase of PCT applicationPCT/DE02/01581, filed 1 May 2002, published 14 Nov. 2002 as WO02/089877, and claiming the priority of German patent application10121949.0 itself filed 5 May 2001.

FIELD OF THE INVENTION

The invention relates to a protective device for a needle having atapered end fitting that can be fitted on a complementary tapered mountof a syringe.

BACKGROUND OF THE INVENTION

In order to inject active substances, syringes are used that have apiston-holding cylinder whose front end is provided is with a central oroffset tapered mount over which can be slipped the tapered seat of anend fitting of a metallic needle. Such syringes are used in largenumbers as so-called single-use syringes that are disposed of after use.

The needle and its end fitting are sealed in a sterile packing and heldin a protective cap formed as a quiver-like sleeve having an open endwhose internal dimension is such that it can fit tightly over the outersurface of the tapered mount. The doctor and medical staff are thusprotected when unpacking the needle and fitting it to the syringe endmount. Once the tapered end fitting is secured to the end mount of thesyringe, the protective cap is pulled off so that an injectablesubstance can be drawn in and then used for a subcutaneous, intravenous,or intramuscular injection or so as to draw body fluids, normally blood,from the patient. In order to prevent needle sticks after use, the capis fitted back over the front needle end, the end fitting of the needleis pulled off the syringe, and the needle inside the protective cap isthrown out. The protective cap is made of plastic and is formed suchthat it does not bend even when severely stressed nor can it expose theneedle tip. There remains however as a result of the small insidediameter of the protective cap the danger that the sharp needle endmisses it to create a substantial danger of injury and a high risk ofinfection.

Medical personal are normally working very quickly and are occupied withthe patient, so that the needle is set aside after use. The used needleis left unprotected on the table and is often tossed as an “open needle”into the trash. When the trash is emptied by the cleaning personnel theneedle pokes easily through the plastic garbage bag and can easilyinjure the personnel dealing with the trash since the needles andsyringes are not visible from outside.

In order to prevent this, German 3,904,559 (US equivalents U.S. Pat.Nos. 4,820,277, 4,909,791, and 4,909,972) proposes a protective sleevefor the needle of a syringe that is formed of two pivotal jaws that canbe locked to each other so as to enclose the syringe needle in atube-like space. The jaws are pivoted on the body of the syringe, on aseparate adapter, or on the bases of a specially designed syringeneedle. The disadvantage of this solution is that it is technicallycomplex and, in particular relative to standard production costs,expensive since the half-shell jaws must be locked together.

It has been proposed for injection needles that the needle be mounted onthe piston in its full-forward position so that it can be drawn backinto the empty cylinder. A complex coupling is needed that not onlyincreases the cost of the end product but also makes using the needlesafter use more difficult, requiring at least particular attention andcareful handling when fitting the needle end fitting to the piston.

It has further been suggested to provide a longitudinally slidablesleeve on the syringe body that is pulled forward after the syringe isused and closed so that the needle point is covered. The disadvantage ofthis system is that the diameter of the syringe in increased (by doublethe wall thickness of the sleeve), the tapered end fitting cannot bemounted at the very end of the syringe body, and it does not rule outthe accidental insertion of a finger into the sleeve. Even such anembodiment is not only expensive because of the considerable materialused, but in particular because of the closure.

OBJECT OF THE INVENTION

It is therefore an object of the present invention to provide aprotective device of the described type that is sufficiently safe, easyto use, and inexpensive to manufacture.

SUMMARY OF THE INVENTION

This object is achieved by the protective device in that the end fittingcarries a sleeve that can be pulled into an end position in which thesleeve completely covers the needle tip. By mounting the sleeve on theend fitting it has to start with the smallest possible diameter so asnot to present a large opening at its end. It can be made with littlematerial. In addition the sleeve can be provided with pulling means thatare no bother and that can be gripped at a safe spacing from the sharpsharpened needle end without any danger of injury.

Thus according to a preferred embodiment of the invention the sleeve isconnected with the tapered end fitting by a weakened region. Theweakened region is formed as a very thin annular region that connectsthe tapered mounting part and the sleeve. Alternatively the sleeve issimply fitted frictionally over the end fitting so that once thefriction is overcome it can be pulled off. This can be achieved forexample by frictionally engaging tapered surfaces. It is significantthat the sleeve is no hindrance when injecting or on drawing bodilyfluids and a sufficient length of the needle is exposed. Once thefriction connection is released or the weakened region is broken, thesleeve can be pulled “forward” in order to safely contain the tip.

Preferably between the sleeve and the end fitting there is a tether,preferably at least one strand or string, whose length is such that itlimits movement of the sleeve away from the end fitting beyond an endposition. The maximum possible length of the string thus forms a stop bymeans of which the sleeve is brought into the desired position.

In order to protect the needle tip when it is unpacked and before it isfitted to the tapered mount of a syringe, a sleeve-shaped protective capis used that is loosely fittable over the needle and that has an openend formed with a lateral slots of a width big enough for the tethers topass through. When for example there are two diametrally oppositestrings fixed on the end fitting, the slits of the protective cap arealso diametrally opposite so that the strings fit through them. At itssimplest, one tether, that is a string or strand, is enough but twotethers are safer since they allow one string to be torn off.

Since the end fitting with two (or more) slots is less stable withrespect to lateral bending, the end fitting has at least two externaltongues that are seatable in complementarily formed pockets formed at anopen end of the protective cap.

According to an alternative solution the sleeve is elastically orplastically extendable such that a top of the needle that is exposedbriefly is completely covered by the sleeve before and after standarduse after drawing a bodily fluid or after injecting an active agent. Forexample the sleeve can be formed over at least a portion of its lengthas a bellows that provides the desires extensibility. The sleeve canalso be formed as a small-diameter extensible telescope. Preferably thesleeve is readily bendable and is made of a material that is strongenough that it cannot be pierced by the needle. If the sleeve is pulledover the needle tip, its bendability leads to a modest deflection to theside so that the pointed needle end in particular its very sharp point,digs into the plastic inner surface of the sleeve and thus effectivelyprevents a retraction of the part that would expose the tip. In order toeffectively protect the pointed needle tip before standard use, asleeve-shaped protective cap is provided for the needle that can befitted over the free end of the sleeve and fit with its taper.

Preferably the sleeve has a tentacle-shaped extension that in a startingcondition, that is before standard use of the needle, ends level with orslightly, e.g. 1 cm, past the needle tip and that is formed as actuatingmeans for applying traction. This can be a plastic strand or a flatextension that is elastic or flexible but bendable so that it does notinterfere with injecting or blood drawing. The tentacle-like extensionsform a system that in fact is used automatically. After inserting theneedle in a vein, artery, or muscle, before bandaging the puncture siteit is standard for the doctor or medical assistant (nurse, aide, etc) toapply a pad to the puncture site as the needle is pulled out.Application of the pad presses down the tentacle-like extensions so thatas the needle is pulled out the sleeve is automatically pulled over theneedle tip. At this time the tentacle-like extensions have done theirjob. The strength of the tentacle-like extensions or their tensilestrength must not be too great so that the tension serves merely tostretch the sleeve along the needle. The tentacle-shaped extensions arepositioned relative to the needle tip, e.g. spaced some 5 mm, such thatwhen the pad is applied to the puncture site these extensions areengaged (right and/or left).

In order to ensure that the needles always lies in the desired plane,the end fitting and the syringe mount are rotation symmetrical.

Preferably the sleeve has an inner wall provided with tongue-shapedspring elements that in an end position covering the needle tip areengageable in pockets on movement of the part and resist oppositemovement of the part. Such “barbs” are for example known for use on theoutside of anchors for screws. In this case the spring elements do notproject radially outward, but radially inward.

According to a further feature of the invention the sleeve has at an endon an inner surface annular niches in which the needle tip fits onreturn movement of the sleeve so as to prevent further return movement.

BRIEF DESCRIPTION OF THE DRAWING

Embodiments of the invention are shown in the drawing. Therein:

FIGS. 1 and 2 show a first embodiment of the invention respectivelybefore and after standard use of the needle in a partly sectionalperspective view;

FIG. 3 is a perspective view of another embodiment according to theinvention;

FIG. 4 is a detail view of a tapered end fitting with a sleeve, tethers,and tentacle-like extensions;

FIG. 5 is a perspective view of a protective cap;

FIG. 6 is a view of detail A of FIG. 3;

FIG. 7 is a section through a sleeve with barbs; and

FIG. 8 is a section through a sleeve with an internal annular recess.

SPECIFIC DESCRIPTION

The syringe shown in FIGS. 1 and 2 is comprised of a cylinder 10 holdinga piston 11 and provided at one end with an eccentric tapered mount overwhich can be fitted a complementary tapered end fitting 16 in which aneedle 12 is imbedded. According to the invention the end fitting 16carries a sleeve or bellows 14 whose front end is provided withtentacle-like extensions 15 that extend parallel to the needle 12 andeven in this case slightly past it. The needle tip and the uncoveredparts are covered by a sleeve-like protective cap 13 whose open rear endis fitted over a complementarily shaped cylindrical or tapered surfaceof the sleeve-like part 14. The needle 12 is thus covered along its fulllength. As a rule the needle 12 is packed with the end fitting 16,protective cap 13, and bellows 14 separately from the cylinder 10 andpiston 11. Once the parts 10 and 11 and the parts 12–16 are separatelyunpacked the tapered end fitting 16 is fitted to the tapered mount ofthe syringe cylinder 10 so that the needle 12 is connected to thecylinder 10. Now the protective cap 13 is pulled off so that the needletip is exposed. After the injectable medicament is drawn in through theneedle 12, the medicament is injected subcutaneously, intravenously, orintramuscularly. As this is done the tentacle-like extensions 15 arepushed easily to the side by the skin and offer no hindrance to theinjection procedure of the needle even with a complex intravenousprocedure. Once the injection is complete, as the needle 12 is withdrawna swab is applied to prevent bleeding. Application of the swab to theskin holds down the tentacle-shaped extensions 15 so that, as thesyringe is backed off, the bellows 14 is expanded to reach the positionof FIG. 2 in which it is pulled over the needle tip. The bendableconstruction of the bellows 14 ensures that, on any movement of theneedle 12 forward, the sleeve 14 bends to the side and is not pierced.When bent to the side as shown in FIG. 2 the needle 12 digs into theinside wall of the sleeve 12 that is formed of such a strong materialthat the needle 12 cannot pierce through it. Even when pushed stronglythe needle 12 will at worst bend or break so that all pointed sharpparts are held inside the sleeve 14.

In the embodiment of FIGS. 3 to 6 the tapered end fitting 16 is providedwith a sleeve part 17 but a joint 18 to it is formed with a very thinwall thickness. A pull on the sleeve 17 ruptures the joint 18 and thusthe connection to the tapered end fitting 16 so that the sleeve 17 canslide along the needle 12 until it uncovers the tip of the needle 12.Here also the tentacle-shaped extensions 15 function on or shortly afterwithdrawal of the needle 12 from the injection site to pull, first tobreak the weakened joint 18 and subsequently to move the sleeve 17 overthe needle tip. Tethers 19 ensure that the part 17 is only moved to theregion of the needle tip. The sleeve 17 has internal pockets 20 in whichspring elements 21 and 27 can engage when the sleeve 17 is moved towardthe tip of the needle 12. FIG. 17 shows the spring element 27 engaged insuch a pocket 20 as well as the spring element 21 when spread. In analternative arrangement shown in FIG. 8 an annular recess or groove 28in the sleeve inner surface is provided forming a tapered widened regionadjacent a restricted-diameter region. When the sleeve-shaped extension17 is pulled past the needle tip, opposite movement of the needleengages the needle tip in the recess 28. FIG. 7 also shows a taperedwidened region 26 that serves for centering the needle in the sleeve.

FIG. 5 shows a protective cap 13 that has on opposite sides two slots 23through which the tethers 10 or the ends of the tentacles 15 can fit(see in particular FIG. 6). In addition and as shown in FIG. 4 twotongues 24 are provided on the end fitting 16 that fit in respectiveunillustrated pockets of the protective cap 13 and prevent thisprotective cap 13 from bending. The protective cap's closed end has athickening 25 to surely prevent any piercing by the sharp needle tip.

1. In combination with a syringe having a body on which is mounted anend fitting fixed to a needle having a tip, a protective devicecomprising: a small-diameter sleeve fitting around the needle and havingan inner end at the end fitting and an opposite outer end, the sleevebeing displaceable from a starting position with the outer end adjacentthe body and exposing the needle tip and an end position with the outerend engaged over the needle tip, the sleeve being formed with at leastone flexible extension having a free outer end generally level with theneedle tip in the starting position; and means including structure forsecuring the sleeve to the end fitting in the starting position, thestructure being sufficiently weak that a traction applied to theflexible extension displaces the sleeve into the end position.
 2. Theprotective device defined in claim 1 wherein the structure is a thinfrangible web connecting the sleeve inner end to the end fitting.
 3. Theprotective device defined in claim 2, further comprising a generallyinextensible tether having one end connected to the end fitting andanother end connected to the sleeve, the tether being dimensioned suchthat it is taut in the end position of the sleeve.
 4. The protectivedevice defined in claim 3, further comprising a stiff end cap fittableover the needle and formed with a slot through which the tether passeswhen the tether is fitted over the needle.
 5. The protective devicedefined in claim 2, wherein the end fitting is formed with at least twooutwardly projecting tongues engaged in the sleeve in the startingposition.
 6. The protective device defined in claim 1 wherein thestructure is flexible and extensible, the structure being longitudinallycompacted in the starting position and longitudinally extended in theend position.
 7. The protective device defined in claim 6 wherein thestructure can telescope.
 8. The protective device defined in claim 6wherein the structure is formed at least partially as a bellows.
 9. Theprotective device defined in claim 6, further comprising a stiff end capfittable over the needle and having an inner end attached to the outerend of the sleeve.
 10. The protective device defined in claim 1 whereinthe end fitting is rotation symmetrical.
 11. The protective devicedefined in claim 1 wherein the sleeve has an inner wall provided withspring tongues directed to resist movement of the sleeve from the endposition into the starting position.
 12. The protective device definedin claim 1 wherein the sleeve outer end is formed with inwardly openpockets dimensioned to catch the needle tip on displacement of thesleeve from the end position to the starting position.
 13. Theprotective device defined in claim 1 wherein the sleeve is provided withlatch means for retaining it in the end position.
 14. The protectivedevice defined in claim 1 wherein the inner sleeve end is inwardlyflared.
 15. The protective device defined in claim 1 wherein theextension is generally parallel to the needle and has an inner endattached to the sleeve inner end.